This invention pertains to a device and method for removing gaseous impurities from a sealed vacuum, and more particularly pertains to a device and method for use in vacuum insulation jackets for vessels or pipes which contain or through which flows a hydrogen containing medium.
Vacuum insulation jackets are used in a variety of applications, such as for example in certain types of commercial industrial solar collectors which absorb solar energy into a chamber containing an organic heat transfer fluid, and in vacuum insulation jackets for underground pipes carrying steam as used in oil drilling systems. It is known that when the vessel or pipe encased in the vacuum insulation jacket contains a hydrogen containing medium, that atomic hydrogen or its isotopes permeates from the hydrogen containing medium through the pipe wall and into the vacuum jacket by way of diffusion. Accumulation of hydrogen in the vacuum jacket degrades the vacuum and destroys its thermal insulating properties due to heat transmission across the vacuum by gaseous conduction. Of course, getter materials are used to remove a variety of gaseous impurities such as carbon monoxide, oxygen, nitrogen, hydrocarbons, etc., from a sealed vacuum. Getter materials are limited however, in their capacity to absorb hydrogen and to maintain a substantially low pressure.
In application Ser. No. 173,189, filed Mar. 23, 1988, now U.S. Pat. No. 4,886,048, assigned to the assignee of the present invention, there is disclosed a hydrogen pump useful for eliminating hydrogen from vacuum insulation jackets. The disclosures of application Ser. No. 173,189, now U.S. Pat No. 4,886,048, are hereby incorporated by reference. In the hydrogen pump invention of said patent, it is necessary for the hydrogen pump to be in contact with the environment, i.e. air, outside the vacuum insulation jacket. While the hydrogen pump works well for vacuum insulated pipe (VIP) installations on commercial solar collectors, it would not be suitable for VIP installations such as underground pipes carrying steam used in oil drilling and recovery operations.